ORCHARD PARK, N.Y. (AP) Buffalo Bills rookie starter Josh Allen has been diagnosed with a sprained right elbow on his throwing arm and is not expected to play at Indianapolis this weekend, a person with direct knowledge told The Associated Press on Tuesday.

The person described Allen's status as being week to week as opposed to being out indefinitely. The person spoke to The AP on the condition of anonymity because the team has not revealed the nature of the injury.

Coach Sean McDermott would only list Allen as week to week on Monday, and wouldn't rule him out from playing this weekend.

The Bills (2-4) were off on Tuesday, and McDermott is next scheduled to address reporters once the team returns to practice Wednesday.

Allen's injury, sustained in the third quarter of a 20-13 loss at Houston on Sunday, leaves Buffalo choosing between turnover-prone Nathan Peterman and newly signed veteran Derek Anderson to start against the Colts (1-5).

Peterman has thrown four interceptions this season, including two in the final two minutes against Houston. The second-year player lost the starting job after faltering badly in a 47-3 season-opening loss at Baltimore.

He's best remembered for throwing five interceptions in the first half of his first start in a 54-24 loss at the Los Angeles Chargers in November.

Anderson is a 12-year veteran who was lured out of semiretirement to sign with Buffalo last week to mentor Allen. The 35-year-old Anderson attempted just eight passes in three appearances with Carolina last season, and hasn't started a game in nearly two years.

Allen was drafted seventh overall out of Wyoming and has a 2-3 record.

Allen bent down and grabbed his arm in pain and stayed in for one more play - an incompletion to Zay Jones - before going down to one knee. He was then spotted yelling out in pain while trainers examined his elbow along the sideline.

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